1. Field of the Invention
The present invention relates to olefin metathesis. More particularly, the present invention relates to olefin metathesis catalysts.
2. General Background of the Invention
The formation of C—C bonds via olefin metathesis (e.g. Ring Closing Metathesis, RCM, or Ring Opening Metathesis Polymerization, ROMP) is a powerful technique in organic synthesis and polymer chemistry.1 Well-defined, single-component metal-carbene complexes of the Grubbs type (RuCl2(═CHR)(PR′3)2 (1) (see FIG. 2) are highly efficient catalyst precursor, moderately air and moisture sensitive and very tolerant of a variety of organic functional groups.2 However, they exhibit low thermal stability and decompose at high temperatures.3 It has been shown that the replacement of one of the phosphine ligand in the Grubbs system with a sterically demanding nucleophilic carbene ligand (e.g., N,N′-bis(mesityl)imidazol-2-ylidene, IMes) (2) (see FIG. 2) leads to increased thermal stability of the catalyst precursor and results in an increased RCM activity towards tri- and tetra-substituted dienes substrates.3,4 
A common drawback of all above-mentioned catalyst precursors is their difficult recovery from reaction mixtures. These usually decompose upon work-up, giving rise to products that are highly colored by ruthenium residues.5 These issues have been addressed by sequestering the ruthenium residues via addition of hydrophilic phosphine ligands6 or lead compounds7 in the work-up procedure, by phosphine derivatization leading to water-soluble olefin metathesis catalysts and applications in biphasic systems8, and by the development of recyclable monomeric9 (5) (see FIG. 2) and dendritic10 ruthenium-based catalyst.
The simpler approach of anchoring an olefin metathesis catalyst to a polymer support should in theory lead to a straightforward recovery of the catalyst by filtration. Attempts have been made to heterogenize Grubbs catalyst by immobilizing it either through bis-phosphine linkages11 or through the carbene moiety.5 The former results in a two orders of magnitude decrease in catalytic activity compared to its homogeneous counterpart; and the latter, although displaying high activity in the initial cycle, exhibit significantly lower activity in subsequent cycles.5 
The use of macroporous polymers as supports for transition metal catalysts has been explored.12 Macroporous resins have a permanent well-developed porous structure even in a dry state.13 Contrary to lightly cross-linked Merrifield resins14, that need swelling solvents to access their interior volume, the pore structure of macroporous resins can be accessed by solvents and reactants without a need for swelling.12 
The following U.S. Patents are incorporated herein by reference:
PAT. NO. Title
U.S. Pat. No. 6,049,017 Enhanced light olefin production
U.S. Pat. No. 6,030,917 Combinatorial synthesis and analysis of organometallic compounds and catalysts
U.S. Pat. No. 5,948,946 Use of sol-gel derived porous microposite of perfluorinated ion-exchange polymer and metal oxide to isomerize terminal olefins
U.S. Pat. No. 5,902,766 Alumoxanes, catalysts utilizing alumoxanes and polymers therefrom
U.S. Pat. No. 5,824,622 Porous microcomposite of perfluorinated ion-exchange polymer and metal oxide, a network of silica, or a network of metal oxide and silica derived via a sol-gel process
U.S. Pat. No. 5,639,900 Thermally activated olefin metathesis catalyst precursor
U.S. Pat. No. 5,606,085 Thermally activated olefin metathesis catalyst precursor
U.S. Pat. No. 5,569,635 Catalyst supports, supported catalysts and methods of making and using the same
U.S. Pat. No. 5,519,101 Process for preparation of unsaturated oligomers or polymers by acyclic olefin metathesis
U.S. Pat. No. 5,403,904 Process for preparation of telechelic difuntional unsaturated oligomers or polymers by acyclic olefin metathesis
U.S. Pat. No. 4,607,022 Olefin conversion catalyst
U.S. Pat. No. 4,547,617 Olefin conversion
U.S. Pat. No. 4,266,085 Olefin disproportionation process
U.S. Pat. No. 4,179,403 Resin-ligand-metal complex compositions